Explanation: These
four panels show x-ray images of expanding cosmic debris clouds,
tens of light-years across, in nearby galaxy the
Large Magellanic Cloud.
The supernova remnants (SNRs) are the results of two types of
stellar
explosions and are arranged in order of apparent age or
the time since light from the initial explosion first reached
planet Earth.
Clockwise starting at the upper left are remnants aged 600 years,
1,500 years, 10,000 years and 13,000 years.
The first three result from a
Type Ia
explosion - the destruction of a
white dwarf star by a thermonuclear
blast triggered by mass accreted from a stellar companion.
The fourth (lower left) is a
Type II
explosion - triggered by the final
collapse of the core of a massive star.
A neutron star, the remnant of the collapsed core,
lies at its center.